In an endless belt conveyor, a conveyor belt passes around end rollers and is supported therebetween on idler rollers. The endless belt normally includes a load-carrying run and a return run. Typically, the load-carrying run is of a trough formation and the supporting idler rollers are arranged in a troughing formation. The endless belt conveyor normally includes a frame structure including two spaced apart longitudinal frame members (commonly known as stringers). The idler rollers are carried on frames which extend between and which are attached to the stringers.
It is on occasions necessary to lift a section of the endless belt This is usually necessary when access is required to an idler roller, or a bank of idler rollers, for servicing, repair or replacement.
Various lifting arrangements have been used for lifting the belt clear of an idler roller. These lifting arrangements include use of a lever, such as a length of wood or crow bar, for levering a section of the belt upwardly clear of a particular idler roller, or use of a hoisting system. Lever systems and hoisting systems are not always convenient to use as they can be difficult to set up and use in confined locations.
Australian Patent No. 580705 discusses a belt lifting device which comprises a top beam for location below, and across, a section of belt to be lifted and a base beam adapted to be placed across, and supported by, lateral frame members located on the longitudinal sides of the conveyor belt. A jack mechanism is provided between the top beam and the base beam, the arrangement being such that operation of the jack mechanism can raise the top beam relative to the base beam thereby to lift the section of belt above the top beam. The jack mechanism is in the form of a scissor jack accommodated between the two beams. Because of the location of the scissor jack, the extent to which the top and base beams can be drawn together to provide a compact arrangement when the device is in a retracted condition is limited. This limitation in compactness can be disadvantageous for storage and transportation, particularly so when the lifting device needs to be carried manually to A location at which it is to be used. Furthermore, the limitation in compactness can present difficulties in circumstances where there is restricted space within the conveyor frame structure in the region below the belt to accommodate the lifting device.